b K. MITSUKURI : STUDIES ON 



band. Along the doi'sal median line of the posterior parts of the 

 first and second limbs of the digestive tube, there is a distinct 

 development of the retc mirahile. The respiratory tree is also 

 well developed, but neither of the branches in any way comes in 

 contact with the blood vessels. 



Calcareous ring as in the figure (textfig. 1 a, h) ; radialia four- 

 pointed, 7 mm. wide. It is comparatively thick, its cross-sec- 

 tion being almost square. When it is looked at from behind, 

 the posterior edge has two (or more ?) teeth on each 

 side of the median incision. Tnterradialia o mm. long, single- 

 pointed. 



Hitherto 7 species of Pseudosticltojms have been described. I 

 am of the opinion that all these are of a very doubtful 

 validity. A thorough re-examination will, I believe, reduce the 

 number. The specimens above described do not agree exactly 

 with any of the species. Nevertheless, I beUeve they agree suf- 

 ficiently closely with Psciiclostichopus trachus Slitter to admit of 

 their identification with it. The chief point of difl"orence is that 

 there are calcareous anal pieces in my specimens, while there 

 are none such described for P. trachus. But it would be very 

 easy to overlook them, especially in largo specimens, and Slxjiter 

 had only two specimens, which were rather large, being respectively 

 18 and 15.5 cm. For the rest, the calcareous ring agrees well. 

 Again, there are no calcareous bodies in the ovarian tubes, although 

 this perhaps is not a very important characteristic. Moreover, 

 the localities given by Sluiter are in seas nearer Japan than 

 those of any other species. On the whole, therefore, I prefer to 

 put my specimens in P. tracJms Sluiter. At the same time, I am 

 prepared to learn at any time that some other species of the genus 

 are synonymous with that species. 



